Flat Roof Rafter Span

For heavy loads 2x4s can span up to 5.

Flat roof rafter span.

For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. 2 are indicated below. Click the button to calculate the stock size needed for this job.

Live load 20 lbs ft 2 956 n m 2. They are nailed securely to exterior wall plates and to each other. The lengths and sizes of joists vary depending on the species and quality of the lumber used. The above spans are based on american softwood lumber standard sizes.

Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. This calculator is to be used as an estimating tool only.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Input the rafter span on the flat eave overhang and pitch of the roof. The tables below give maximum spans for rafters and beams. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof.

Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. The rafters in a flat roof serve as ceiling joists for the space below. The imposed uniformly distributed live load in the main span. 1 ft 0 3048 m.

For light load roofs 24 o c. This is set by the roof use you selected in the previous screen and cannot be modified. Rafter stock size calculator. Also available for the android os.

Dead load weight of structure and fixed loads 15 lbs ft 2. Live load is weight of furniture wind snow and more. 1 psf lb f ft 2 47 88 n m 2. Span calculator for wood joists and rafters also available for the android os.

Click the button to calculate the stock size needed for this job. 1 in 25 4 mm. Live load overhang kpa. Input the rafter span on the flat eave overhang and pitch of the roof.

Wood beam calculator american wood council website rafter and joist span faq. The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof. 2 4 rafters can span up to 7.